SOLUTION STRUCTURE AND DIRECT IMAGING OF FIBRONECTIN ADSORPTION TO SOLID-SURFACES BY SCANNING FORCE MICROSCOPY AND CRYOELECTRON MICROSCOPY

In this study, we present the scanning force and electron microscopic visualization of single molecules of fibronectin either frozen hydrate d or adsorbed onto metallic and polymeric surfaces with different soli d surface tensions. The surfaces were characterized by dynamic contact angle measurements, X-ray photo emission spectroscopy (XPS or ESCA) a nd scanning force microscopy. The proteins were prepared by fast prote in liquid chromatography (FPLC) and characterized by gel electrophores is. Protein films on surfaces were investigated by surface plasmon res onance spectroscopy and directly imaged by scanning force microscopy. The spreading of the adsorbed fibronectin revealed dependence on the c hemical composition and the solid surface tension. Structure of fibron ectin in solution as well as on solid interface appeared as an extende d straight strand as obtained by imaging with electron and scanning pr obe microscopies. Imaging of DNA was performed by scanning force micro scopy to test the accuracy and reproducibility of our measurements. Th e measured contour lengths were accurate and the larger widths were ca used by convolution of the tip shape and sample. Frictional forces dur ing the scan have been of significant contribution in the imaging mech anism. Moreover, this work demonstrated that scanning force microscopy can be used for mapping the orientation and organization of protein f ilm adsorbed onto various surfaces at the nanoscale.